1. Field of the Invention
The present invention relates to a conductive film, and more particularly, to a conductive film suitable for a touch panel electrode. In addition, the invention relates to a touch panel including the conductive film and a display device including the touch panel.
2. Description of the Related Art
In recent years, a conductive film which is used in a touch panel has drawn attention as a conductive film provided in a display device. This touch panel is mainly applied to a small device, such as a PDA (portable information terminal) or a mobile phone. Increasing the size of the touch panel will be considered for application to, for example, personal computer displays.
Regarding a future trend, since electrodes according to the related art are made of indium tin oxide (ITO) (for example, JP2009-259003A), they have high resistance and a large size. As a result, the transmission speed of a current between the electrodes is low and a response speed (the time from the touch of a fingertip to the detection of a touch position) is low.
A structure will be considered in which a plurality of grids formed by thin wires made of metal (thin metal wires) are arranged to form an electrode to reduce surface electrical resistance. For example, JP2004-221564A discloses a method for forming thin metal wires. In addition, a conductive film for a touch panel has been proposed which has a conductive pattern including a plurality of large grids, each of which is a combination of a plurality of small grids, and a medium grid that electrically connects the large grids (see JP2012-163933A). JP2012-163933A also discloses an example in which a first conductive film having a conductive pattern (first conductive pattern) that is arranged in one direction and a second conductive film having a conductive pattern (second conductive pattern) that is arranged in the other direction (a direction perpendicular to the one direction) are stacked.